1. Field of the Invention
The present invention relates to a card made of a thermoplastic material and having visually recognizable safety markings. The invention relates also to a method of manufacturing a card made of a thermoplastic material and having visually recognizable safety markings.
2. Description of the Prior Art
Recently, printed cards made of a plastics material have been widely accepted as credit cards, as money substrate and also as identification cards, which cards can convey a service, a value or an authorization of access. The partial information which identifies the owner of such card as well as the features, which subordinate such card under a certain organization or system is made in form of printings, embossments, punchings or in form of a magnet-, laser- or holographic information on this card. It is thereby relatively simple to copy the outer appearance of such card. It is obvious that accordingly there exists the possibility of a misuse of such cards which replace the longer the more cash transactions, which copying can be made presently without large efforts. Thereby specifically the public has no possibility to ascertain by itself if such card is genuine. Accordingly, cards have been developed and are known which are compound cards having a paper layer enclosed between two plastic layers. The paper layer is provided with a safety printing such as is known in common paper money and comprises such as is the well known case in paper money a watermark which is visible when a person views through the card. Furthermore, parts of the surfaces of the plastic may be provided with a printed pattern. Such cards do provide indeed a higher safety, however have several shortcomings. It has been proven that due to the compound consisting of different materials such as paper and plastic the embossments of the final card will generate a deformation. Due to the tension force exerted on the card it will show an arching or convexity in direction of the embossing, which detrimentally influences the automatic legibility of the above mentioned information in case such information is present thereon. Furthermore, the construction of such known card allows still an illegal intervention thereof. For this reason it is possible to open the card along the paper layer which allows, say, manipulation of this paper layer or it is possible to dissolve the protecting plastic layers by means of a solvent such that thereafter the paper layer is freely accessible. It is now due to above reasons not desired to have such cards made out of a paper-plastic compound. In contrast, it is desired to provide cards made completely out of a plastics material which comprise the necessary safety features. Because, however, such cards preferably have planar surfaces, no design thereof has been known until now which contains adequate safety features such as are, for instance, known to be present in modern bills with paper money which measures presupposed often irregular surface structures. Furthermore, there exist no cards made of a plastics material which have safety features which are visible by viewing through such card, which do not have other significant drawbacks.